Antibiotic Resistance Genes in drinking water of China: Occurrence, distribution and influencing factors. - Related Documents




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778001.0000Antibiotic Resistance Genes in drinking water of China: Occurrence, distribution and influencing factors. Drinking water samples were collected from 71 cities, including 28 provincial capital cities or municipalities, 20 prefecture cities and 23 counties, of 31 provincial-level administrative regions in China from July to August in 2017. Futhermore, 24 Antibiotic Resistance Genes (ARGs), 16S rRNA and 2 integrase genes were quantified by qPCR to investigate the pollution degree of ARGs. The results revealed that the 16S ranged from 10(5) - 10(8) copies/100 mL in the drinking water, and its treatment process could effectively remove bacteria. Moreover, sulfonamides-ARGs were the most prevalent ARGs in the drinking water of China, and the abundance of bla(TEM) ranked top five in all cities among the selected ARGs, indicating that the pollution condition of the genes should be aroused more attention. The data of qPCR and correlation analyses indicated that intI1 played a more crucial role than intI2 in the propagation of ARGs in the drinking water. Additionally, the pollution degree of ARGs among different city types showed no significant difference.202031683044
777810.9998Distribution of antibiotic resistance in the effluents of ten municipal wastewater treatment plants in China and the effect of treatment processes. Municipal wastewater treatment plant (WWTP) effluents represent an important contamination source of antibiotic resistance, threatening the ecological safety of receiving environments. In this study, the release of antibiotic resistance to sulfonamides and tetracyclines in the effluents of ten WWTPs in China was investigated. Results indicate that the concentrations of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) ranged from 1.1 × 10(1) to 8.9 × 10(3) CFU mL(-1) and 3.6 × 10(1) (tetW) to 5.4 × 10(6) (tetX) copies mL(-1), respectively. There were insignificant correlations of the concentrations of ARB and ARGs with those of corresponding antibiotics. Strong correlations were observed between the total concentrations of tetracycline resistance genes and sulfonamide resistance genes, and both of which were significantly correlated with intI1 concentrations. Statistical analysis of the effluent ARG concentrations in different WWTPs revealed an important role of disinfection in eliminating antibiotic resistance. The release rates of ARB and ARGs through the effluents of ten WWTPs ranged from 5.9 × 10(12) to 4.8 × 10(15) CFU d(-1) and 6.4 × 10(12) (tetW) to 1.7 × 10(18) (sul1) copies d(-1), respectively. This study helps the effective assessment and scientific management of ecological risks induced by antibiotic resistance discharged from WWTPs.201728088530
533820.9998Characterisation of microbial communities and quantification of antibiotic resistance genes in Italian wastewater treatment plants using 16S rRNA sequencing and digital PCR. The spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in humans, animals and environment is a growing threat to public health. Wastewater treatment plants (WWTPs) are crucial in mitigating the risk of environmental contamination by effectively removing contaminants before discharge. However, the persistence of ARB and ARGs even after treatment is a challenge for the management of water system. To comprehensively assess antimicrobial resistance dynamics, we conducted a one-year monitoring study in three WWTPs in central Italy, both influents and effluents. We used seasonal sampling to analyze microbial communities by 16S rRNA, as well as to determine the prevalence and behaviour of major ARGs (sul1, tetA, bla(TEM), bla(OXA-48), bla(CTX-M-1 group), bla(KPC)) and the class 1 Integron (int1). Predominant genera included in order: Arcobacter, Acinetobacter, Flavobacterium, Pseudarcobacter, Bacteroides, Aeromonas, Trichococcus, Cloacibacterium, Pseudomonas and Streptococcus. A higher diversity of bacterial communities was observed in the effluents compared to the influents. Within these communities, we also identified bacteria that may be associated with antibiotic resistance and pose a significant threat to human health. The mean concentrations (in gene copies per liter, gc/L) of ARGs and int1 in untreated wastewater (absolute abundance) were as follows: sul1 (4.1 × 10(9)), tetA (5.2 × 10(8)), bla(TEM) (1.1 × 10(8)), bla(OXA-48) (2.1 × 10(7)), bla(CTX-M-1 group) (1.1 × 10(7)), bla(KPC) (9.4 × 10(5)), and int1 (5.5 × 10(9)). The mean values in treated effluents showed reductions ranging from one to three log. However, after normalizing to the 16S rRNA gene (relative abundance), it was observed that in 37.5 % (42/112) of measurements, the relative abundance of ARGs increased in effluents compared to influents. Furthermore, correlations were identified between ARGs and bacterial genera including priority pathogens. This study improves our understanding of the dynamics of ARGs and provides insights to develop more effective strategies to reduce their spread, protecting public health and preserving the future efficacy of antibiotics.202438750766
351530.9998Impact of reclaimed water irrigation on antibiotic resistance in public parks, Beijing, China. The abundance and distribution of antibiotics and antibiotic resistance genes (ARGs) in soils from six parks using reclaimed water in Beijing, China, were characterized. Three classes of commonly used antibiotics (tetracycles, quinolones, and sulfonamides) were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The highest concentrations of tetracyclines and quinolones were 145.2 μg kg(-1) and 79.2 μg kg(-1), respectively. Detected tetG, tetW, sulI, and sulII genes were quantified by quantitative PCR. ARGs exhibited various abundances for different park soils. The integrase gene (intI1) as an indicator of horizontal gene transfer potential was also detected in high abundance, and had significant positive correlation with tetG, sulI, and sulII genes, suggesting that intI1 may be involved in ARGs dissemination. Both sulII and intI1 clones had high homology with some classes of pathogenic bacteria, such as Klebsiella oxytoca, Acinetobacter baumannii, Shigella flexneri, which could trigger potential public health concern.201424071635
777040.9998Mitigation of antibiotic resistance in a pilot-scale system treating wastewater from high-speed railway trains. Wastewater from high-speed railway trains represents a mobile reservoir of microorganisms with antibiotic resistance. It harbors abundant and diverse antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). This study investigated the removal of ARB and ARGs in a pilot-scale reactor, which consisted of an anaerobic/anoxic/oxic process, anaerobic/anoxic/aerobic process, and ozone-based disinfection to treat 1 m(3)/day wastewater from an electric multiple unit high-speed train. Further, the high prevalence of two mobile genetic elements (intI1 and Tn916/615) and five ARGs (tetA, tetG, qnrA, qnrS, bla(NDM-1), and ermF) was investigated using quantitative PCR. Significant positive correlations between ARGs (tetA, bla(NDM-1), and qnrA) and intI1 were identified (R(2) of 0.94, 0.85, and 0.70, respectively, P < 0.01). Biological treatment could significantly reduce Tn916/1545 (2.57 logs reduction) and Enterococci (2.56 logs reduction of colony forming unit (CFU)/mL), but the qnrS abundance increased (1.19 logs increase). Ozonation disinfection could further significantly decrease ARGs and Enterococci in wastewater, with a reduction of 1.67-2.49 logs and 3.16 logs CFU/mL, respectively. Moreover, food-related bacteria families which may contain opportunistic or parasitic pathogens (e.g., Moraxellaceae, Carnobacteriaceae, and Ruminococcaceae) were detected frequently. Enterococci filtered in this study shows multi-antibiotic resistance. Our study highlights the significance to mitigate antibiotic resistance from wastewater generated from high-speed railway trains, as a mobile source.202031864053
350650.9998Occurrence and distribution of antibiotic resistance genes in sediments in a semi-enclosed continental shelf sea. Extensive and improper overuse of antibiotics resulted in the prevalence of antibiotic resistance genes (ARGs). As the typical semi-enclosed continental shelf sea, the Bohai Sea has been considered as one of the most polluted marine areas in China. However, no comprehensive investigation on the spatial distribution of ARGs in sediments from the Bohai Sea has been reported. A large-scale sampling was performed in the Bohai Sea areas. The abundances of ARGs (6 classes, 29 ARG subtypes), class 1 integron-integrase gene (intI1), hmt-DNA and 16S rRNA gene were evaluated. IntI1 was detected with higher abundances in coastal areas ranging from 2.8 × 10(5) to 2.5 × 10(8) copies/g. The total ARGs abundances varied over 3 orders of magnitude in different sampling sites with the maximum at 4.9 × 10(8) copies/g. Sulfonamides resistance genes were ubiquitous and abundant with the abundances ranging from 5.7 × 10(4) to 1.8 × 10(7) copies/g, and quinolones resistance genes varied greatly in different samples. The contour map demonstrated that ARGs were more abundant in the Laizhou Bay, the south of Bohai Bay and the eastern of central sea basin. Most of the target ARG subtypes were detected with 100% detection frequencies. The genes of sul1, sul2 and tetX were detected with both higher absolute and relative abundance, while the abundance of β-lactams ARG subtypes was lower. Principal component analysis (PCA) and redundancy analysis (RDA) indicated that no significant differences in the ARGs abundance existed in different samples, and the sediment qualities played important roles in the distribution of ARGs. Bacterial communities were investigated and 768 strong and significant connections between ARGs and bacteria were identified. The possible hosts of ARGs were revealed by network analysis with higher relative abundance in coastal areas than the sea.202032325606
778160.9998Untreated HWWs Emerged as Hotpots for ARGs. Hospital wastewaters (HWWs) are reported to be hotspots for antibiotics and antibiotic-resistant bacteria. However, limited information involves the impact of these effluents on dissemination of antibiotic-resistance genes (ARGs). In this study, therefore, seasonally collected HWWs were monitored for overall bacterial load and seven ARGs aadA, tetA, cmlA, sul1, qnrS, ermB and bla (CTX-M )by using quantitative polymerase chain reaction method. Overall bacterial 16S rRNA copy number was found to be the lowest in winter with 10(3 )copy number/mL, while the highest copy number, with 10(5 )copy number/mL, was observed in both summer and spring. All hospitals tested displayed similar seasonal ARG copy number profile of aadA > tetA > cmlA ≈ sul1 > ermB ≈ qnrS > bla (CTX-M). The results indicated that untreated HWWs were hotspots for ARGs and required attention before discharging into public sewer.202031965225
351470.9997Potential risks of microplastics combined with superbugs: Enrichment of antibiotic resistant bacteria on the surface of microplastics in mariculture system. Microplastics have become emerging pollutants and served as potential vectors for harmful bacteria, while rare information on the emergency and propagation of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) on the surface of microplastics is available. This study investigated the enrichment of ARB, especially multi-antibiotic resistant bacteria (MARB), on the surface of microplastics in mariculture system. Polyethylene terephthalate accounted for the highest proportion (75%) in the collected microplastics. The counts of cultivable ARB in microplastic samples were 6.40 × 10(6)-2.48 × 10(8) cfu/g, which were 100-5000 times higher than those in water samples. The ratios of cultivable ARB to total cultivable bacteria from microplastic samples were higher than those from water samples. High-throughput sequencing showed that the diversity and abundance of cultivable ARB in the microplastic samples was high with the predominant bacterial genera of Vibrio, Muricauda and Ruegeria. Total 160 MARB isolates were obtained and most of isolates were obtained from the microplastic samples. MARB isolates resisting or intermediating to four and three antibiotics accounted for much higher proportions in the microplastic samples, and the higher percentage of antibiotic resistance was to penicillin, sulfafurazole, erythromycin and tetracycline. The dominant multiple antibiotic resistance profile was TET-SFX-ERY-PEN, which accounted for 25.4% in microplastic samples and 23.9% in water samples. In typical MARB isolates, the positive detection rate of ARGs was up to 80.0% in microplastic samples while that was 65.3% in water samples. Five types of class 1 integrons (intI1) associated gene cassette arrays and seven types of gene cassettes were detected in microplastic samples, which were more than those in water samples. These results revealed that microplastics were hazardous pollutants for the enrichment of ARB, especially superbugs, and the spread of antibiotic resistance.202031670243
777180.9997Can chlorination co-select antibiotic-resistance genes? Selective pressures, such as chemical or heavy metal pollution, may co-select for bacterial antibiotic resistance in the environment. However, whether chlorination in water treatment can co-select antibiotic-resistant bacteria is controversial. In this study, high capacity quantitative polymerase chain reaction (qPCR) analysis was applied to target almost all known antibiotic-resistance genes (ARGs) (282 types) and 13 mobile genetic elements (MGEs) in bacteria detected in secondary effluents from a municipal wastewater treatment plant after chlorination. The results revealed that 125 unique ARGs were detected in non-chlorinated samples, and the number decreased (79-91 types) as the chlorine concentration was increased. Moreover, 7.49 × 10(4)-3.92 × 10(7) copies/100 ml water reduction of ARGs occurred with 4 mg Cl2/l. Considering the relative abundance of ARGs (i.e., ARG copies normalized to 16S rRNA gene copies), 119 ARGs decreased in response to chlorination, whereas only six ARGs, such as dfrA1, tetPB-03, tetPA, ampC-04, tetA-02, and erm(36), were potentially enriched by 10.90-, 10.06-, 8.63-, 6.86-, 3.77-, and 1.09-fold, respectively. Furthermore, the relative abundance of 12 detected MGEs was lower after chlorination. Therefore, chlorination was effective in reducing ARGs and MGEs rather than co-selecting them.201627192478
351290.9997Profiling of intracellular and extracellular antibiotic resistance genes in tap water. Antibiotic resistance genes (ARGs) have gained global attention due to their public health threat. Extracelluar ARGs (eARGs) can result in the dissemination of antibiotic resistance via free-living ARGs in natural environments, where they promote ARB transmission in drinking water distribution systems. However, eARG pollution in tap water has not been well researched. In this study, concentrations of eARGs and intracellular ARGs (iARGs) in tap water, sampled at Tianjin, China, were investigated for one year. Fourteen eARG types were found at the highest concentration of 1.3 × 10(5) gene copies (GC)/L. TetC was detected in 66.7% of samples, followed by sul1, sul2, and qnrA with the same detection frequency of 41.7%. Fifteen iARGs (including tetA, tetB, tetM, tetQ, tetX, sul1, sul2, sul3, ermB, blaTEM, and qnrA) were continuously detected in all collected tap water samples with sul1 and sul2 the most abundant. Additionally, both eARG and iARG concentrations in tap water presented a seasonal pattern with most abundant prevalence in summer. The concentration of observed intracellular sulfonamide resistance genes showed a significantly positive correlation with total nitrogen concentrations. This study suggested that eARG and iARG pollution of drinking water systems pose a potential risk to human public health.201930448547
3513100.9997Tetracyclines, sulfonamides and quinolones and their corresponding resistance genes in the Three Gorges Reservoir, China. The Three Gorges Project significantly impacted water quality and ecological balance in this area. The special engineered aquatic environment could be an important reservoir for antibiotic resistance genes (ARGs). Fifteen ARGs corresponding to three groups of antibiotics (tetracyclines, sulfonamides and quinolones) were determined in surface water, soil and sediment in this study. Total concentrations of antibiotics ranged from 21.55 to 536.86ng/L, 3.69 to 438.76ng/g, 15.78 to 213.84ng/g in water, soil and sediment, respectively. Polymerase chain reaction (PCR) of ARGs revealed the presence of two sulfonamide resistance genes (sul1, sul2), five tetracycline resistance genes (tetA, tetB, tetM, tetQ, tetG) and class 1 integron gene (intI1) in all samples. And the relative abundance of sulfonamide resistance genes was generally higher than tetracycline resistance genes in three matrices. Significant correlations (p<0.05) were found between the concentrations of intI1 and ARGs (tetA, tetB, tetM, tetQ, tetG, sul1, sul2), indicating intI1 may facilitate the proliferation and propagation of these genes. Redundancy analysis (RDA) showed distribution of ARGs was related to the certain antibiotics residues, which may exert selective pressure on bacteria and thus enrich the abundance of ARGs. The results of this study could provide useful information for both better understanding and management of the contamination caused by ARGs and related antibiotics in engineered aquatic environments.201829727994
7774110.9997Antibiotic-resistant genes and antibiotic-resistant bacteria in the effluent of urban residential areas, hospitals, and a municipal wastewater treatment plant system. In this study, we determined the abundance of 8 antibiotics (3 tetracyclines, 4 sulfonamides, and 1 trimethoprim), 12 antibiotic-resistant genes (10 tet, 2 sul), 4 antibiotic-resistant bacteria (tetracycline, sulfamethoxazole, and combined resistance), and class 1 integron integrase gene (intI1) in the effluent of residential areas, hospitals, and municipal wastewater treatment plant (WWTP) systems. The concentrations of total/individual targets (antibiotics, genes, and bacteria) varied remarkably among different samples, but the hospital samples generally had a lower abundance than the residential area samples. The WWTP demonstrated removal efficiencies of 50.8% tetracyclines, 66.8% sulfonamides, 0.5 logs to 2.5 logs tet genes, and less than 1 log of sul and intI1 genes, as well as 0.5 log to 1 log removal for target bacteria. Except for the total tetracycline concentration and the proportion of tetracycline-resistant bacteria (R (2) = 0.330, P < 0.05), there was no significant correlation between antibiotics and the corresponding resistant bacteria (P > 0.05). In contrast, various relationships were identified between antibiotics and antibiotic resistance genes (P < 0.05). Tet (A) and tet (B) displayed noticeable relationships with both tetracycline and combined antibiotic-resistant bacteria (P < 0.01).201525323405
3510120.9997Spatiotemporal profile of tetracycline and sulfonamide and their resistance on a catchment scale. Tetracyclines and sulfonamides are the two classes of antibiotics commonly used in the medical, industrial and agricultural activities. Their extensive usage has caused the proliferation and propagation of resistant bacteria (ARB) and resistance genes (ARGs) in the environment. In this study, the occurrence and distribution of tetracyclines (TC, OTC and CTC) and sulfonamides (SMX, SCX and TMP), their associated ARB and ARGs were quantified in water and sediments collected from the mainstream of Liaohe River, northeast China. The average concentration of tetracyclines was higher in May, while the concentration of sulfonamides was slightly higher in October. The highest concentrations of the total tetracyclines and sulfonamides in sediments were 2.7×10(3) ng/g and 2.1×10(2) ng/g respectively detected in May. All detected ARGs were found generally with high abundance. The tetA, tetB and tetE genes were dominant (4.4×10(-2) to 9.8×10(-1) copies of tet genes/copies of 16S rRNA genes) in total communities, and the average abundance of sul genes was expressed above 10(-1) in the water samples in May and October. Redundance analysis (RDA) and principle component analysis (PCA) indicated that the antibiotic residue was the most important contributor to the level of tetracycline and sulfonamide resistance genes, and some hydrogeological conditions (e.g. flow rate, intersection settlement) influenced the distribution of resistance genes. Results from this study could help understand the proliferation and propagation of antibiotic resistance on a river catchment scale and mitigate the potential risks to public health.201830029318
7237130.9997Dominant denitrifying bacteria are important hosts of antibiotic resistance genes in pig farm anoxic-oxic wastewater treatment processes. The anoxic-oxic (A/O) wastewater treatment process that is widely used in pig farms in China is an important repository for antibiotic resistance genes (ARGs). However, the distribution of ARGs and their hosts in the A/O process has not been well characterized. In this study, the wastewaters in the anoxic and oxic tanks for A/O processes were collected from 38 pig farms. The concentrations of 20 subtypes of ARGs, 5 denitrification-related genes, 2 integrons, and bacterial community composition were investigated. Bacterial genome binning was performed using metagenome sequencing. In this study, 20 subtypes of ARGs and integrons were detected in all sampling sites. A total of 16 of the 20 subtypes of ARGs were detected with the highest abundance in anoxic tanks, and sul1 was detected with a maximum average abundance of 19.21 ± 0.24 log(10) (copies/mL). Cooccurrence patterns were observed for some genes in the pig farm A/O process, such as sul1 and intl1, sul1 and tetG, and tetO and tetW. There was a significant cooccurrence pattern between the dominant denitrifying bacteria and some ARGs (bla(TEM), ermB, tetC, tetH and tetQ), so the dominant denitrifying bacteria were considered to be potential ARG hosts. In addition, 170 highly abundant bacterial genome bins were assembled and further confirmed that the denitrifying bacteria Brachymonas, Candidatus Competibacter, Thiobacillus and Steroidobacter were the important ARG hosts in the pig farm A/O process, providing a useful reference for the surveillance and risk management of ARGs in pig farm wastewater.202032615347
5340140.9997Hospital wastewaters: A reservoir and source of clinically relevant bacteria and antibiotic resistant genes dissemination in urban river under tropical conditions. The occurrence and dissemination of antibiotic resistant genes (ARGs) that are associated with clinical pathogens and the evaluation of associated risks are still under-investigated in developing countries under tropical conditions. In this context, cultivable and molecular approaches were performed to assess the dissemination of bacteria and the antibiotic resistance genes in aquatic environment in Kinshasa, Democratic Republic of the Congo. Cultivable approach quantified β-lactam, carbapenem resistant, and total Escherichia coli and Enterobacteriaceae in river sediments and surface waters that receive raw hospital effluents. The molecular approach utilized Quantitative Polymerase Chain Reaction (qPCR) to quantify the total bacteria and the richness of relevant bacteria (Escherichia coli, Enterococcus, and Pseudomonas), and antibiotic resistance genes (ARGs: bla(OXA-48), bla(CTX-M), bla(IMP), bla(TEM)) in sediment samples. Statistical analysis were employed to highlight the significance of hospital contribution and seasonal variation of bacteria and ARGs into aquatic ecosystems in suburban municipalities of Kinshasa, Democratic Republic of the Congo. The contribution of hospitals to antibiotic resistance proliferation is higher in the dry season than during the wet season (p < 0.05). Hospital similarly contributed Escherichia coli, Enterococcus, and Pseudomonas and ARGs significantly to the sediments in both seasons (p < 0.05). The organic matter content correlated positively with E. coli (r = 0.50, p < 0.05). The total bacterial load correlated with Enterococcus, and Pseudomonas (0.49 < r < 0.69, p < 0.05). Each ARG correlated with the total bacterial load or at least one relevant bacteria (0.41 < r < 0.81, p < 0.05). Our findings confirm that hospital wastewaters contributed significantly to antibiotic resistance profile and the significance of this contribution increased in the dry season. Moreover, our analysis highlights this risk from untreated hospital wastewaters in developing countries, which presents a great threat to public health.202032470679
5333150.9997Antibiotic resistance profile of wastewater treatment plants in Brazil reveals different patterns of resistance and multi resistant bacteria in final effluents. Wastewater treatment plants (WWTPs) are recognized as important sources of Antibiotic Resistant Bacteria (ARBs) and Antibiotic Resistant Genes (ARGs), and might play a role in the removal and dissemination of antimicrobial resistance (AMR) in the environment. Detailed information about AMR removal by the different treatment technologies commonly applied in urban WWTPs is needed. This study investigated the occurrence, removal and characterization of ARBs in WWTPs employing different technologies: WWTP-A (conventional activated sludge-CAS), WWTP-B (UASB reactor followed by biological trickling filter) and WWTP-C (modified activated sludge followed by UV disinfection-MAS/UV). Samples of raw sewage (RI) and treated effluent (TE) were collected and, through the cultivation-based method using 11 antibiotics, the antibiotic resistance profiles were characterized in a one-year period. MAS was effective in reducing ARB counts (2 to 3 log units), compared to CAS (1 log unit) and UASB/BTF (0.5 log unit). The composition of cultivable ARB differed between RI and TE samples. Escherichia was predominant in RI (56/118); whilst in TE Escherichia (31/118) was followed by Bacillus (22/118), Shigella (14/118) and Enterococcus (14/118). Most of the isolates identified (370/394) harboured at least two ARGs and in over 80 % of the isolates, 4 or more ARG (int1, blaTEM, TetA, sul1 and qnrB) were detected. A reduction in the resistance prevalence was observed in effluents after CAS and MAS processes; whilst a slight increase was observed in treated effluents from UASB/BTF and after UV disinfection stage. The multi-drug resistance (MDR) phenotype was attributed to 84.3 % of the isolates from RI (27/32) and 63.6 % from TE (21/33) samples and 52.3 % of the isolates (34/65) were resistant to carbapenems (imipenem, meropenem, ertapenem). The results indicate that treated effluents are still a source for MDR bacteria and ARGs dissemination to aquatic environments. The importance of biological sewage treatment was reinforced by the significant reductions in ARB counts observed. However, implementation of additional treatments is needed to mitigate MDR bacteria release into the environment.202336240935
7764160.9997Air-drying beds reduce the quantities of antibiotic resistance genes and class 1 integrons in residual municipal wastewater solids. This study investigated whether air-drying beds reduce antibiotic resistance gene (ARG) concentrations in residual municipal wastewater solids. Three laboratory-scale drying beds were operated for a period of nearly 100 days. Real-time PCR was used to quantify 16S rRNA genes, 16S rRNA genes specific to fecal bacteria (AllBac) and human fecal bacteria (HF183), the integrase gene of class 1 integrons (intI1), and five ARGs representing a cross-section of antibiotic classes and resistance mechanisms (erm(B), sul1, tet(A), tet(W), and tet(X)). Air-drying beds were capable of reducing all gene target concentrations by 1 to 5 orders of magnitude, and the nature of this reduction was consistent with both a net decrease in the number of bacterial cells and a lack of selection within the microbial community. Half-lives varied between 1.5 d (HF183) and 5.4 d (tet(X)) during the first 20 d of treatment. After the first 20 d of treatment, however, half-lives varied between 8.6 d (tet(X)) and 19.3 d (AllBac), and 16S rRNA gene, intI1, and sul1 concentrations did not change (P > 0.05). These results demonstrate that air-drying beds can reduce ARG and intI1 concentrations in residual municipal wastewater solids within timeframes typical of operating practices.201323909386
5358170.9997Abundance of antibiotics, antibiotic resistance genes and bacterial community composition in wastewater effluents from different Romanian hospitals. Antimicrobial resistance represents a growing and significant public health threat, which requires a global response to develop effective strategies and mitigate the emergence and spread of this phenomenon in clinical and environmental settings. We investigated, therefore, the occurrence and abundance of several antibiotics and antibiotic resistance genes (ARGs), as well as bacterial community composition in wastewater effluents from different hospitals located in the Cluj County, Romania. Antibiotic concentrations ranged between 3.67 and 53.05 μg L(-1), and the most abundant antibiotic classes were β-lactams, glycopeptides, and trimethoprim. Among the ARGs detected, 14 genes confer resistance to β-lactams, aminoglycosides, chloramphenicol, macrolide-lincosamide-streptogramin B (MLSB) antibiotics, sulfonamides, and tetracyclines. Genes encoding quaternary ammonium resistance and a transposon-related element were also detected. The sulI and qacEΔ1 genes, which confer resistance to sulfonamides and quaternary ammonium, had the highest relative abundance with values ranging from 5.33 × 10(-2) to 1.94 × 10(-1) and 1.94 × 10(-2) to 4.89 × 10(-2) copies/16 rRNA gene copies, respectively. The dominant phyla detected in the hospital wastewater samples were Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. Among selected hospitals, one of them applied an activated sludge and chlorine disinfection process before releasing the effluent to the municipal collector. This conventional wastewater treatment showed moderate removal efficiency of the studied pollutants, with a 55-81% decrease in antibiotic concentrations, 1-3 order of magnitude lower relative abundance of ARGs, but with a slight increase of some potentially pathogenic bacteria. Given this, hospital wastewaters (raw or treated) may contribute to the spread of these emerging pollutants in the receiving environments. To the best of our knowledge, this study quantified for the first time the abundance of antibiotics and ARGs in wastewater effluents from different Romanian hospitals.201728347610
5370180.9997Airborne antibiotic resistance genes in Hong Kong kindergartens. Antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) have become a critical global public health issue in this century. There is increasing evidence for the presence and transmission of ARGs by air transmission. In this research, ARGs and ARB in air conditioner filter dust (AC dust) and urine samples from 55 kindergarten children in 17 kindergartens and nearby 10 soil samples in Hong Kong were analyzed. The results showed the presence of 16 ARG subtypes and the mobile genetic element (MGE) intI1 in AC dust, and 12 ARG subtypes in the soil samples. ARGs presenting resistance to sulfonamide (6.9 × 10(-3)-0.17) (expressed as relative abundance of the 16 S rRNA genes) were most abundant followed by macrolides (1.8 × 10(-3)-3.3 × 10(-2)), sul1, sul2 (sulfonamide), ermF (macrolides) and intI1 genes in AC dust in 17 kindergartens. For soil samples, 12 ARG subtypes and the intI1 were detected, and the genes providing resistance to sulfonamide (1.6 × 10(-3)-2.7 × 10(-1)) were the most abundant ARGs in the 10 soil samples, followed by tetracycline (ND-1.4 × 10(-2)). Multi-resistant bacteria with sul1, sul2, intI1, or tetQ were detected in all AC dust samples and some urine samples. Based on bacterial genera and ARG co-occurrence network analysis and Hong Kong's special geographical location and cultural environment, there might be two origins for the ARGs detected in the kindergartens: β-lactam/macrolide ARGs mainly derived from human medicine use and tetracycline/sulfonamide ARGs mainly from other areas, as well as IntI1 may play a role in the spread of ARGs in Hong Kong. The widely detection of ARGs in AC dust in kindergartens in Hong Kong highlights the need for the improvement of management measures.202032041021
7777190.9997Fate of antibiotic resistant cultivable heterotrophic bacteria and antibiotic resistance genes in wastewater treatment processes. Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are emerging contaminants of environmental concern. Heterotrophic bacteria in activated sludge have an important role in wastewater treatment plants (WWTPs). However, the fate of cultivable heterotrophic ARB and ARGs in WWPTs process remains unclear. In the present study, we investigated the antibiotic-resistant phenotypes of cultivable heterotrophic bacteria from influent and effluent water of three WWTPs and analysed thirteen ARGs in ARB and in activated sludge from anoxic, anaerobic and aerobic compartments. From each influent or effluent sample of the three plants, 200 isolates were randomly tested for susceptibility to 12 antibiotics. In these samples, between 5% and 64% isolates showed resistance to >9 antibiotics and the proportion of >9-drug-resistant bacteria was lower in isolates from effluent than from influent. Eighteen genera were identified in 188 isolates from influent (n=94) and effluent (n=94) of one WWTP. Six genera (Aeromonas, Bacillus, Lysinibacillus, Microbacterium, Providencia, and Staphylococcus) were detected in both influent and effluent samples. Gram-negative and -positive isolates dominated in influent and effluent, respectively. The 13 tetracycline-, sulphonamide-, streptomycin- and β-lactam-resistance genes were detected at a higher frequency in ARB from influent than from effluent, except for sulA and CTX-M, while in general, the abundances of ARGs in activated sludge from two of the three plants were higher in aerobic compartments than in anoxic ones, indicating abundant ARGs exit in the excess sledges and/or in uncultivable bacteria. These findings may be useful for elucidating the effect of WWTP on ARB and ARGs.201525950407